Thermal Solar Capacitor System

ABSTRACT

The present invention relates to a zero-emission renewable heating system utilizing a thermal energy capacitor system using solar power as its source of heat, and more particularly, to a solar thermal capacitor system using an solar concentrators and a molten salt cell with thermal storage capability.

FIELD OF THE INVENTION

The present invention relates to a zero-emission renewable heatingsystem utilizing a thermal energy capacitor system using solar power asits source of heat, and more particularly, to a solar thermal capacitorsystem using an solar concentrators and a molten salt cell with thermalstorage capability.

BACKGROUND OF THE INVENTION

The desire to decrease and ultimately eliminate dependence on limitedenergy resources has stimulated research into clean and renewable waysto conserve resources and utilize renewable energy sources. Solar powerhas become a viable option because it is a clean form of energyproduction and there is a potentially limitless supply of solarradiation. To that end, it is estimated the solar energy flux from thesun is approximately 2.7 megawatt-hours per square meter per year incertain advantageous areas of the world. With this tremendous amount offree and clean energy available, and the desire to reduce dependence onlimited resources, solar power production is now, more than ever, beingreviewed as an important means to help meet the energy consumptiondemands in various parts of the world.

Molten salt is used in solar power tower systems because it is liquid atatmosphere pressure, it provides an efficient, low-cost medium in whichto store thermal energy, its operating temperatures are compatible withtodays high-pressure and high-temperature steam turbines, and it isnon-flammable and nontoxic. In addition, molten salt is used in thechemical and metals industries as a heat-transport fluid, so experiencewith molten-salt systems exists for non-solar applications.

Molten salt is also an efficient heat capacitor, with low heatdissipation. It retains thermal energy very effectively over time andoperates at very high temperatures. It is relatively inexpensive andplentiful, and generally non-toxic. Thermal storage is widely regardedas the future for the renewable energy campaign because, unlike manyintermittent renewable resources such as wind energy, it offers a“zero-emissions” technology.

Several molten salt heat transfer fluids have been used for solarthermal systems. The binary Solar Salt mixture was used at the 10 MWeSolar Two central receiver project in Barstow, Calif. It will also beused in the indirect TES system for the Andasol plant in Spain. Amongthe candidate mixtures, it has the highest thermal stability and thelowest cost, but also the highest melting point. Hitec HTS® has beenused for decades in the heat treating industry. This salt is thermallystable at temperatures up to 454° C., and may be used up to 538° C. forshort periods, but a nitrogen cover gas is required to prevent the slowconversion of the nitrite component to nitrate. The currently availablemolten salt formulations do not provide an optimum combination ofproperties, freezing point, and cost that is needed for a replacementheat transfer fluid in parabolic trough solar fields. Therefore, thework summarized in this report sought to develop an heat transfer fluidthat will better meet the needs of parabolic trough plants.

In many areas of the world, thermal energy for heating and cooking usecoal or wood or such other resource. These resources generally are notrenewable and emit significant waste. Accordingly, a need exists for athermal energy generation system capable of efficient energy collection,with high temperature capability, and with the ability to storecollected energy in areas where resources are extremely limited.

SUMMARY OF THE INVENTION

The present invention is directed to a solar power thermal energycapacitor capable of storing heat energy wherein sun light is convertedto thermal energy. The solar power system includes a solar concentratorsystem, which concentrates the sunlight onto thermal capacitor. Theconcentrated sunlight heats a surface of the thermal capacitor.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a schematic of a solar thermal capacitor system according to apreferred embodiment of the present invention;

FIG. 2 is a schematic of an alternate solar thermal capacitor systemaccording to a preferred embodiment of the present invention;

FIG. 3 is a drawing of a linear Fresnel concentrator and a linearthermal capacitor;

FIG. 4 depicts variations of mirror concentrators as the solarconcentrator component;

FIG. 5 a schematic of an alternate solar thermal capacitor system havingmultiple solar concentrators according to a preferred embodiment of thepresent invention;

FIG. 6 depicts variations of thermal capacitor cells;

FIG. 7 is a sectional perspective of a solar thermal capacitor system;

FIG. 8 illustrates a stand-alone system utilizing a large Fresnel lensto heat thermal capacitor according to the teachings of the presentinvention;

FIG. 9 is a schematic of a solar thermal capacitor system havingmultiple collection systems according to the teachings of the presentinvention;

FIG. 10 is a schematic of a solar thermal capacitor system illustratingthe tracking of the sun by the system according to the teachings of thepresent invention;

FIG. 11 is a schematic of an alternate solar thermal capacitor systemhaving multiple collection systems according to the teachings of thepresent invention;

FIG. 12 is a schematic of a complete solar thermal capacitor systemcapable of tracking the sun according to the teachings of the presentinvention;

FIG. 13 illustrates the use of a solar thermal capacitor system duringthe day and night in a house for cooking and heating according to theteachings of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

With reference to FIG. 1, a solar thermal capacitor system 10 inaccordance with a preferred embodiment of the present invention isshown. The solar thermal capacitor system 10 includes a solar collectionsystem 12 and a thermal capacitor 16. The solar collection system 12gathers sunlight and concentrates the sunlight to a thermal capacitor16. The thermal capacitor 16 uses molten salt 14 to store the thermalenergy from the solar collection system 12.

The solar collection system 12 has a solar concentrator 18. The solarconcentrator 18 gathers sunlight and concentrates the sunlight. Thesolar concentrator 18 includes a lens 22 or a mirror. In one preferredform, the lens 22 is a Fresnel lens (FIG. 1) or a magnifying lens (FIG.2). The sunlight strikes the lens 22 and is focused onto the thermalcapacitor 16 below the lens 22. The lens 22 is coupled to a supportstructure 26 that supports the lens 22 and operably coupled to a base.The thermal capacitor 16 can be independent of support structure 26(FIG. 1) or dependent from the support structure 26 (FIG. 2).

The concentrating component (interchangeably referred to also as lens ormirror) 18, which can help focus the spatially decomposed solar spectrumonto the thermal capacitor 16, can be provided in any number of usefulconfigurations. Preferred designs utilize optical lens to concentratediffracted light.

The optical component used in the solar concentrators typically providesa 2-10000 fold concentration, more preferably 5-1000, more preferably10-500-fold concentration of the sun irradiance, most preferably greaterthan a 10-fold concentration. The concentrator can take different formssuch as, but not limited to, rectangular, polygonal or circular shapes(including arcs, cylinders, semi-cylinders, planes, etc), and can bemade of any suitable materials. Concentrators can include, e.g., aconvex lens (both biconvex and plano-convex), positive or negativemeniscus lens, a gradient refractive index lens, a Fresnel lens,standard magnifying lens, or other type of light concentrating lens,and/or the like (see FIG. 2). The choice of lens can be influenced bydesign requirements such as aspect ratio, weight, cost and thereliability desired in the concentrator structure, as further describedbelow.

Concentrator 18 is mounted on the very top of the assembly andconcentrates the light energy from the sun through top aperture. Theconcentration of the light energy need not be at a focal point whenentering the aperture. The lens may be a standard magnifying lens (FIG.2), a Fresnel type lens (FIG. 1) or other type of light concentratinglens and may be round, elliptical, semi-elliptical (FIG. 3), rectangular(or rectangular with rounded edges), triangular, or irregular in generalshape when looking at the direction of the light path (from the side).The lens is designed to fit the top of the assembly as well as focus asmuch light on the thermal capacitor 16 of the device. The lens can takethe general structure of the housing or be embedded within the housing(FIG. 2).

The shape of the concentrator can be modified to adjust theconcentration and direction of the light energy to optimize its use soas to increase efficiency and maximize heat generation. In oneembodiment, the lens 22 in FIG. 3 is shaped to concentrate the sunlightlinearly creating a focal line at the top of the thermal capacitor 16 oroff-focus below the thermal capacitor. More preferably, the concentratorwill concentrate the light at the top of the thermal capacitor 16 togenerate maximum heat.

With reference to FIG. 4, the focal length of a lens in air can becalculated from the lensmaker's equation:

${\frac{1}{f} = {\left( {n - 1} \right)\left\lbrack {\frac{1}{R_{1}} - \frac{1}{R_{2}} + \frac{\left( {n - 1} \right)d}{n\; R_{1}R_{2}}} \right\rbrack}},$

where

f is the focal length of the lens,

n is the refractive index of the lens material,

R1 is the radius of curvature of the lens surface closest to the lightsource,

R2 is the radius of curvature of the lens surface farthest from thelight source, and

d is the thickness of the lens (the distance along the lens axis betweenthe two surface vertices).

To increase the incident light's intensity you have to change material(higher refractive index) or decrease the focal length increasing thelens curvature (higher aberrations) or increase the optical quality.

By example and without limitation, the concentrator is formed of glass,acrylic, silicone, plastic, polycarbonate, or fluoropolymers (e.g.,Ethylene Tetrafluoroethylene (ETFE), or another transparent material tohave a focal length structured for focusing or concentrating the lightenergy from the sun through top aperture. Preferably, solar concentratoris formed of material with thought to such attributes as resistance towarping or corrosion, breaking, cracking, scratching, shattering,melting, extreme heat, oxidation and discoloration; little lightabsorption or loss; heat absorption, low cost, ease of manufacturing,strength, weight, availability, toxicity, magnification, regionalavailability of resources and manufacturing capabilities, combinationsthereof, and the like. For example, ETFE film is utilized in a oneembodiment of the present invention as it is 1% the weight, transmitsmore light and costs 24% to 70% less to install compared to glass.Commercially deployed brand names of ETFE include Tefzel by DuPont,Fluon by Asahi Glass Company, Neoflon ETFE by Daikin, and Texlon byVector Foiltec.

In other embodiments of concentrator components, concentrators areassembled from cast components, such as cast acrylic or other polymer(e.g., acrylate, methacrylate, polyethylene terephthalate (PET),polycarbonate) or a combination of cast components and extrudedcomponents or from optical components manufactured by various othermanufacturing processes. Exemplary cast acrylic components includeHESA-GLAS from Notz Plastics AG and available from G-S Plastic Opticslocated 23 Emmett Street in Rochester, N.Y. 14605. In an alternateembodiment, solar concentrators are manufactured from extrudablematerial such as various plastics e.g. Fluoroplastic, Fluoropolymer orFluorocarbon. Exemplary extruded plastics include extruded acrylics andextruded polycarbonates available from Bay Plastics Ltd (UnitedKingdom). Lenses can be created using known techniques, includingtraditional polishing or computer-controlled milling equipment (CNC)that can turn out large complex pieces from single pieces of glass.Exemplary lens manufacturers include Kenteh Optical Co., Ltd. (Taiwan)and E-Tay Industrial Co., Ltd. (Taiwan), WuXi Bohai Optical ApparatusElectronic Co., Ltd. (China), Wenzhou Mingfa Optics Plastics Co., Ltd.(China), CDGM Glass Co., Ltd. (China), Ikeda Lens Industrial Co., Ltd(Japan), etc.

Other choices of concentrators can include mirrors that reflect sunlightunto a single point or points (See FIG. 4), such as with a) linearparabolic mirrors; b) compound linear fresnel mirrors; c) compoundparabolic mirror(s); d) mirror array; e) compound hyperbolic mirrors; f)compound elliptic mirrors; and the like. These contractors can have asecond concentration stage to further improve the quality or magnitudeof concentration.

As shown in FIG. 5, multiple lenses 22 and 24 can be employed in seriesto refract the light through each layer of lens. Each layer refracts thelight 26 and reduces the distance between the 1st lens 22 and thethermal capacitor 16.

The sunlight is concentrated from the solar concentrator system 18 tothe thermal capacitor 16 as shown in FIG. 2. The concentrated sunlight14 heats the thermal capacitor 16 directly or through an absorber 30. Asshown in FIG. 6, the thermal capacitor can be various shapes, but ispreferably in a shape that is portable and modular. Such shapes includecylindrical (FIGS. 6A and 6B), spherical, a block (FIG. 6C), cube, disc(FIG. 6D), rectangular (FIG. 6E), and other such shapes that lend thethermal capacitor to be transferred between different applications. Forcost purposes, the cell can be a can and shaped accordingly.

In a preferred embodiment, solar collection system 12 can concentratesunlight unto the entire thermal capacitor 16 or a portion thereof. Asshown in FIGS. 1 and 2, the upper portion of the thermal capacitor is anabsorptive material 30. The absorptive material 30 absorbs the solarenergy and aids in the distribution of the resulting thermal energy tothe molten salt 14. The absorptive material 30 may include, for example,metal, graphitic absorbers or heat absorbers, including IR or UVabsorbers. The absorber 30 can be as simple as coloring the top a heatabsorbing color (e.g., black or other dark color) to a heat transmissiontube 32 that transmits the heat throughout the thermal capacitor 16.Heat tubes 32 can be used to receive the thermal energy from theabsorption of concentrated sunlight and transfer the energy into themolten salt 14.

Infrared absorbing materials and coatings are well known in the art(see, e.g., U.S. Pat. App. No. 20090029057 and WIPO Patent ApplicationWO/2008/071770). For example, a conductive silver coating which, whenduring the thermal fusing (firing) of the coating to a metal, glass,silicon, polymer, ceramic or ceramic glass enamel substrate, providesinfrared absorption properties over an extended temperature range. Othermaterials include nanoparticle coatings. Depending on the infraredabsorption resonance wavelength (i.e. the wavelength at which thenanoparticles primarily absorb) and the width of the absorbance range(i.e. the wavelength range over which the nanoparticles causeabsorption), one can divide nanoparticles in different groups. A firstgroup of nanoparticles absorbs infrared energy in a broad band in thewavelength range above 1000 nm. Examples comprise indium oxide, tinoxide, antimony oxide, zinc oxide, aluminum zinc oxide, tungsten oxide,indium tin oxide (ITO) nanoparticles, antimony tin oxide (ATO), antimonyindium oxide or combinations thereof. A second group of nanoparticlesabsorbs infrared in the near infrared. The nanoparticles of the secondgroup absorb infrared in the range 780-1000 nm. Examples ofnanoparticles of the second group comprise hexaboride nanoparticles,tungsten oxide nanoparticles or composite tungsten oxide particles.Alternatively, a metal or other conductive material can be used toabsorb heat generated by infrared. IR can cause substantial heat andabsorbance of the IR can be dissipated through the housing by thismethod. Accordingly, infrared-absorbing materials can be placed on anoutermost layer of the housing wall, preferably outside or exterior tothe refractor component, more preferably on a metal, glass or othermaterial layer.

The thermal capacitor 16 can be further surrounded by an insulationlayer 34 that reduces heat loss to the atmosphere and facilitatehandling of the thermal capacitor 16 by a tool or by hand. Theinsulation layer 34 enables the thermal capacitor 16 to maintaintemperature even if the sunlight has diminished or the thermal capacitor16 is exposed to colder temperatures. Preferably, the insulation isrugged and resistant to rough environmental conditions.

Referring to FIG. 6, the molten salt fuel 14 is stored in a thermalcapacitor cell 40, which acts to contain molten salt fuel 14. Thermalcapacitor cell 40 can be lined with an insulation layer 34. Thermalcapacitor cell 40 is capable of withstanding high temperatures, forexample, temperatures of at least approximately 1200 degrees Fahrenheit(° F.), preferably at least approximately 1500° F., more preferably atleast approximately 2000° F., and most preferably at least approximately2500° F. Preferably, thermal capacitor cell 40 is resistant to corrosionand repetitive fluctuations in heat. Suitable materials for constructingthermal capacitor cell 40 include, but are not limited to: copper basedalloys, nickel based alloys, iron based alloys, and cobalt based alloys,but also include such compounds such as aluminum, nickel, iron,titanium, stainless steel, or other metal or alloy. Examples of suitablecommercially available nickel based alloys include: Hastelloy X,Hastelloy N, Hastelloy C, and Inconel 718, available from Special MetalsInc., Conroe, Tex. Examples of suitable commercially available ironbased alloys include: A-286 and PM2000, available from MetallwerkePlansee, Austria. An example of a suitable commercially available cobaltbased alloy includes: Haynes 25, available from Haynes InternationalInc., Windsor, Conn. Other compounds include ceramics or refractorymaterials, or other such compound. Preferably the material is common andcheap to manufacture or use. The thermal capacitor may have a barrierlayer to reduce corrosion, for example a barrier layer comprisingtungsten (W), platinum (Pt), titanium carbide (TiC), tantalum carbide(TaC), titanium oxide (for example, TiO2 or Ti4O7), copper phosphide(Cu2P3), nickel phosphide (Ni2P3), iron phosphide (FeP), and the like,or may comprise particles of such materials, preferably which is stillcapable of transferring heat.

The products of high temperature corrosion can potentially be turned tothe advantage of the engineer. The formation of oxides on stainlesssteels, for example, can provide a protective layer preventing furtheratmospheric attack, allowing for a material to be used for sustainedperiods at both room and high temperature in hostile conditions. Suchhigh temperature corrosion products in the form of compacted oxide layerglazes have also been shown to prevent or reduce wear during hightemperature sliding contact of metallic (or metallic and ceramic)surfaces.

Plating, painting, and the application of enamel are the most commonanti-corrosion treatments. They work by providing a barrier ofcorrosion-resistant material between the damaging environment and the(often cheaper, tougher, and/or easier-to-process) structural material.Aside from cosmetic and manufacturing issues, there are tradeoffs inmechanical flexibility versus resistance to abrasion and hightemperature. Platings usually fail only in small sections, and if theplating is more noble than the substrate (for example, chromium onsteel), a galvanic couple will cause any exposed area to corrode muchmore rapidly than an unplated surface would. For this reason, it isoften wise to plate with a more active metal such as zinc or cadmium.

Other methods for providing corrosion protection include anodizing,controlled permeability formwork, cathodid protection methods, and thelike.

Possible molten salts 14 that can be used include both pure inorganicand organic materials, and eutectic and non-eutectic mixtures. Suchmaterials could have cationic or positively charged components such asalkali metals, alkaline earth metals, aluminum, gallium, indium,germanium, tin transition metals, lanthanide metals, phosphonium,ammonium, sulfinium, arsenium, and stibium ions including polyalkyl andpolyaryl substituted species. The anionic or negatively chargedcomponents could include halides, oxides, sulfides, nitrates,carbonates, carboxylates, silicates, aluminates, sulfates, phosphates,arsenates, borates, alkoxides, and aryl and alkyl sulfonates.

The molten salt medium 14 of solar thermal capacitor 16 is a molten saltcapable of being heated to high temperatures. The molten salt used inthe thermal capacitor is capable of being heated to high temperatures,for example, to a temperature of at least approximately 1200 degreesFahrenheit (° F.), preferably at least approximately 1500° F., and morepreferably at least approximately 1700° F., or above approximately 1800°F. Most preferred are salts that are not liquid at ambient temperature,but salts that are liquid (having a melting point) above ambienttemperature, e.g., non-ionic liquids. Alternatively, molten salt used inthe thermal capacitor are salts that have melting points above ambienttemperature. Inspection of published phase diagrams revealed thatternary mixtures of NaNO3 and KNO3 with several alkali and alkalineearth nitrates have quite low melting points. The eutectic of LiNO3,NaNO3 and KNO3 melts at 120° C., while a mixture of Ca(NO3)2, NaNO3 andKNO3 melts at about 133° C. Several eutectic systems containing threeconstituents are liquids as low as 52° C. Other salts, are for example,low-melting point salts described in U.S. Pat. No. 7,588,694(incorporated herein).

The molten salt can be salts composed of alkaline earth fluorides andalkali metal fluorides, and combinations thereof. Suitable elements ofthe molten salt include: Lithium (Li), Sodium (Na), Potassium (K),Rubidium (Rb), Cesium (Cs), Francium (Fr), Beryllium (Be), Magnesium(Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Radium (Ra), chlorine(Cl), bromine, iodine, Cyanide, Hydroxides, Nitrates, and Fluorine (F).

Common salt-forming cations include:

Ammonium NH4+ Calcium Ca2+ Iron Fe2+ and Fe3+ Magnesium Mg2+ PotassiumK+ Pyridinium C5H5NH+

Quaternary ammonium NR4+

Sodium Na+

Common salt-forming anions (parent acids in parentheses where available)include:

Acetate CH3COO− (acetic acid)Carbonate CO32− (carbonic acid)Chloride Cl− (hydrochloric acid)Citrate HOC(COO—)(CH2COO—)2 (citric acid)

Cyanide C≡N− (N/A)

Nitrate NO3− (nitric acid)Nitrite NO2− (nitrous acid)Phosphate PO43− (phosphoric acid)Sulfate SO42−(sulfuric acid)

Examples of suitable fluoride molten salts include, but are not limitedto: FLiNaK, FLiBe, FLiNaBe, FLiKBe, and combinations thereof. The saltcan further contain a metal such as scandium, yttrium, titanium,zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum,tungsten, manganese, technetium, rhenium and lanthanoid.

In a preferred method, the present invention is directed to a moltensalt bath including at least two types selected from the groupconsisting of lithium, sodium, potassium, rubidium, cesium, beryllium,magnesium, calcium, strontium, and barium; at least one type selectedfrom the group consisting of fluorine, chlorine, bromine, cyanide, andiodine; at least one element selected from the group consisting ofscandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium,tantalum, chromium, molybdenum, tungsten, manganese, technetium, rheniumand lanthanoid (hereinafter, this element may also be referred to as“heavy metal”); and an organic polymer including at least one type of abond of carbon-oxygen-carbon and a bond of carbon-nitrogen-carbon.

In one embodiment, molten salts preferred are salts that are readilyavailable, cheap, and bountiful, for example rock or halite salts, orsalts primarily composed of sodium chloride (generally, having a meltingpoint greater than 801° C., or 1474° F.).

In an alternative embodiment, the molten salt 14 is a 60/40 mixture ofsodium and potassium nitrate, commonly called saltpeter. The salt meltsat 430° F. and is kept liquid at 550° F. in an insulated thermalcapacitor cell. However, the molten salt 42 could also be a saltcarbonates (e.g., Na2CO3, sodium carbonate & other carbonates oflithium, potassium, etc.). Alternative salts include combinations ofnitrates (e.g., potassium (KNO3), Sodium (NANO3)) and nitrites (e.g.,sodium (NaNO2), K—Na—Ca Nitrate mixtures, a Eutectic mixture (46:24:30)with a melting point of 160° C.; K—Na—Li Nitrate Mixture with a meltingpoint as low as 120° C., HITEC, a combination of NaNO2, NaNO3, KNO3(40:7:53) with a melting point of approximately 142° C.; or 45.5 wt %potassium nitrate (KNO3) and 54.5% sodium nitrite (NaNO2), and the like.

The thermal capacitor cells 40 are surrounded by an insulation layer 34or insulation barrier (e.g., structure) that reduces heat loss to theatmosphere. In particular, high wind speed contributes to heat loss, asthe high winds produce convective losses, and a recessed structure ispreferable.

In a preferred embodiment, the molten salt 14 in the thermal capacitor16 is capable of retaining heat for several hours if not several days.The salt liquefies upon reaching at or above it's melting point. If theconcentrated sunlight is sufficient, the salt will liquefy to becomemolten salt, which does not require the solar concentrator to trace thetraveling sun. A concentrator 12 affixed perpendicular to the thermalcapacitor 16 may be sufficient to melt the salt 14. It may not benecessary to heat the thermal capacitor 16 throughout the day. However,in certain environments or conditions, it may be preferred for the solarconcentrator 12 to follow or track the sun and heat the thermalcapacitor 16 throughout the day. As shown in FIG. 7, the solarconcentrator system 18 includes a lens 22 to concentrate sunlight. Thesunlight strikes the lens 22 and is focused onto the thermal capacitor16 below the lens 22. The lens 22 is coupled to a support structure 26that supports the lens 22 and the thermal capacitor 16. The supportstructure 26 is further coupled to a pivot assembly 28. The pivotassembly 28 enables the lens 22 to be adjusted to track the sun as thesun travels across the sky and heat the thermal capacitor 16.Specifically, the pivot assembly 28 provides two axes of rotation forthe lens 22, as known in the art.

In an alternate embodiment, molten salt can be any crystalline moleculethat can be liquefied using solar heat. Sugars, for example are readilyavailable and can be made into molten sugars. Preferred are compoundsthat can crystallize upon cooling and liquefied upon heating.

Support can be made of any material readily available and sturdy enoughto support the other components, including wood, metals and the like.

As shown in FIG. 8, the pivot assembly 28 is rotatably coupled to a base50. The base 50 is affixed to a ground surface and the thermalcapacitors 16 remain stationary until they are needed. The lens 22 isadjusted to track the sun. The thermal capacitors 16 can be shaped toaccommodate shifting focal points, e.g., multiple thermal capacitorcells, a rectangular cell or a base that can retain heat. A controller(not shown) can be coupled to the solar concentrator system 12 thatcontrols the pivot assembly 28 so that it causes the lens 22 to trackthe sun across the sky. In a preferred embodiment, the base 50 holdingthe thermal capacitors 16 is built of heat absorbing material and/orpainted to absorb heat. It may or may not be necessary to heat 50 thebase to a temperature sufficient to melt the salt. In preferredembodiments, the base is built to provide further insulation to thecapacitor cell, for example to encapsulate or embed 52 the thermalcapacitor 16 (See FIG. 9). The base can be painted black and be made ofheat absorbing material such as concrete or metals.

Alternatively, it may be preferred for the solar concentrator 12 tofollow the sun 60 and heat the thermal capacitor 16 throughout the day.As shown in FIG. 10, the solar concentrator system 12 includes a lens toconcentrate sunlight. The sunlight 60 strikes the lens 22 and is focusedonto the thermal capacitor 16 below the lens 22. The lens 22 is coupledto a support structure 26 that supports the lens 22 and the thermalcapacitor 16. The support structure 26 is further coupled to a pivotassembly 28. The pivot assembly 28 enables the lens 22 to be adjusted totrack the sun as the sun travels across the sky and heat the thermalcapacitor. Specifically, the pivot assembly 28 provides two axes ofrotation for the lens 22, as known in the art.

In yet an alternate embodiment, multiple solar concentrators can beutilized to heat multiple fuel cells 16 as shown in FIG. 11. The rows ofsolar concentrator systems are constructed with thermal capacitor. FIG.12 shows multiple lens 22 to concentrate light onto multiple thermalcapacitors 16. The lens 22 are coupled to a support structure 26 thatsupport the lens 22 and the base 50, which supports the thermalcapacitor cells 16. As represented in FIG. 12, the base 50 and the lens22 sit in parallel planes. The base 50 is affixed to a pivot assembly.The pivot assembly 28 enables the lens 22 and the base to be adjusted totrack the sun as the sun travels across the sky. Specifically, the pivotassembly 28 provides two axes of rotation for the lens 22, as known inthe art. To heat the specific thermal capacitor cell, the sun must lieapproximately perpendicular to the lens and base. A thermal capacitorcan contain molten salt 16 b or salt that has been cooled, and likelycrystallized 16 a. In an alternate system, the lens and the base are notin parallel planes. One skilled in the art will readily appreciate thatthe solar thermal capacitor system 10 can be scaled to accommodate awide range of demands for solar power.

As shown in FIG. 1, the solar concentrator system 18 includes a lens 22or a mirror. In one preferred form, the lens 22 is a Fresnel lens. Thesunlight 14 strikes the lens 22 and is focused onto the thermalcapacitor XX below the lens 22. The lens 22 is coupled to a supportstructure 26 that supports the lens 22. The support structure 26 isfurther coupled to a pivot assembly 28. The pivot assembly 28 isrotatably coupled to a base 50. A controller 52 coupled to the solarconcentrator system 12 controls the pivot assembly 28 so that it causesthe lens 22 to track the sun across the sky. More specifically, thecontroller 52 drives a motor (not shown) associated with the pivotassembly 28 to pivot lens 22 as needed.

FIG. 13 shows the solar thermal capacitor system in operation over a dayand evening cycle. If sufficient solar thermal condition exists, thesunlight 14 strikes the lens 22 of the solar concentrator system 12. Thelens 22 concentrates the sunlight to the focus, which is essentially atthe aperture. The sunlight passes through the aperture unto the absorber30. The thermal energy collected by the absorber 30 is absorbed and theresulting thermal energy is transferred into the salt 14 by the heatexchanger tubes 32. During the day, the molten salt in the thermalcapacitor cells are heated to a temperature from the concentratedsunlight above the melting point of the molten salt. Some of the thermalcapacitor cells will contain salt in its liquid state and othercapacitor cells will contain salt not melted, in its solid or crystalform. These must be heated above the salts melting point to be used inits application. Thermal capacitors can have a handle or slot to enableeasy safe transport of the capacitors from one location to another.Thermal capacitors containing salt that has been cooled are returnedback to solar thermal capacitor system to recycle into heating process.This process will repeat as long as a solar power generation conditionexists.

As shown in FIG. 13, the thermal capacitor 16 are used as heating fuelcells to use in stoves 70 to cook food or to warm houses 80. In apreferred embodiment, devices are contemplated that can conduct and/ortransmit the heat for its intended use, e.g., cooking or heating. Astove, for example, can be used for both cooking and heating. Thermalcapacitor cells with molten salt replace thermal capacitor cells withsalt in its solid form. Utilizing invention thermal capacitor cellsprovide a renewable fuel cell that does not emit lethal gas. Aninsulator can be placed on the outside of thermal capacitor cell toavoid burning. Alternatively, or in parallel, thermal capacitor cellscan be moved by tools that are developed specifically for the fuel cellor as simple as a stick.

In an alternate embodiment (not shown), solar thermal capacitor systemcan be tied into a heating system for houses. Thermal capacitors can beplaced in long tubes under or in the structure of a house (permanentlyor by replacement) and heated with a solar concentration system.

In an preferred embodiment of the present invention, the molten saltthermal capacitors are also used as battery fuel cells. Accordingly, theinvention further comprises an anode and cathode connection to enablecharging. Molten salt batteries are a of class high temperature electricbattery that use molten salts as an electrolyte. They offer both ahigher energy density through the proper selection of reactant pairs aswell as a higher power density by means of a high conductivity moltensalt electrolyte. They are used in services where high energy densityand high power density are required. These features make rechargeablemolten salt batteries a promising technology for powering electricvehicles. High operating temperatures of 400° C. (752° F.) to 700° C.(1,292° F.) typically would bring problems of thermal management andsafety, and place more stringent requirements on the rest of the batterycomponents. In the present invention, when used in extreme environmentsor environments with limited resources, high operating temperatures arepermissible.

While there are many different types currently being researched, theusual characteristics is to employ a mixture of various salt carbonates(e.g., Na2CO3, sodium carbonate & other carbonates of lithium,potassium, etc.) as the electrolyte of a battery called a fuel cell.High temperature rechargeable molten salt batteries have been known thatuse transition metal sulfide cathodes. LiAl alloy anode, and a moltenlithium-salt electrolyte. Molten salt cells are a class of primary celland secondary cell high temperature electric battery that use moltensalts as an electrolyte. They offer both a higher energy density throughthe proper selection of reactant pairs as well as a higher power densityby means of a high conductivity molten salt electrolyte. They are usedin services where high energy density and high power density arerequired.

Sodium is attractive because of its high reduction potential of −2.71volts, its low weight, its non-toxic nature, its relative abundance andready availability and its low cost. In order to construct practicalbatteries, the sodium must be used in liquid form. Since the meltingpoint of sodium is 98° C. (208° F.) this means that sodium basedbatteries must operate at high temperatures, typically in excess of 270°C. (518° F.). [citation needed]

Sodium-sulfur battery and lithium sulfur battery comprise two of themore advanced systems of the molten salt batteries. The NaS battery hasreached a more advanced developmental stage than its lithiumcounterpart; it is more attractive since it employs cheap and abundantelectrode materials. Thus the first commercial battery produced was thesodium-sulfur battery which used liquid sulfur for the positiveelectrode and a ceramic tube of beta-alumina solid electrolyte (BASE)for the electrolyte.

The ZEBRA battery operates at 250° C. (482° F.) and utilizes moltensodium aluminum chloride (NaAlCl4), which has a melting point of 157° C.(315° F.), as the electrolyte. The negative electrode is molten sodium.The positive electrode is nickel in the discharged state and nickelchloride in the charged state. Because nickel and nickel chloride arenearly insoluble in neutral and basic melts, intimate contact isallowed, providing little resistance to charge transfer. Since bothNaAlCl4 and Na are liquid at the operating temperature, asodium-conducting β-alumina ceramic is used to separate the liquidsodium from the molten NaAlCl4.

For comparison, LiFePO4 lithium iron phosphate batteries store 90-110Wh/kg and the more common LiCoO2 lithium ion batteries store 150-200Wh/kg. Nano Lithium-Titanate Batteries store energy and power of (116 Wh& 72 Wh/kg) and (1,250 W & 760 W/kg).

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

We claim:
 1. A solar thermal capacitor system, comprising a solarconcentrator and a portable thermal capacitor containing molten salt. 2.The solar thermal capacitor system of claim 1, wherein said solarconcentrator includes a lens or mirror to concentrate the sunlight. 3.The solar thermal capacitor system of claim 2, wherein said lens is achosen from a magnifying lens or a Fresnel type lens.
 4. The solarthermal capacitor system of claim 1, wherein said mirrors or lens isaffixed on a support structure.
 5. The solar thermal capacitor system ofclaim 1, wherein said thermal capacitor is portable and modular cell. 6.The solar thermal capacitor system of claim 1, wherein said thermalcapacitor includes an absorptive material to absorb solar energy.
 7. Thesolar thermal capacitor system of claim 1, wherein said thermalcapacitor further includes an insulation layer to reduce radiant thermalheat loss.
 8. The solar thermal capacitor system of claim 1, wherein themolten salt is stored in a thermal capacitor cell that is corrosionresistant and capable of withstanding multiple repetitive fluctuationsin heat.
 9. The solar thermal capacitor system of claim 1, wherein thethermal capacitor is lined with a corrosion resistant barrier.
 10. Thesolar thermal capacitor system of claim 1, wherein the molten salt is anabundant non-ionic liquid salt that is cheap with can crystallize uponcooling with a melting point greater than ambient temperature.
 11. Thesolar thermal capacitor system of claim 1, wherein the molten salt iscomposed of alkaline earth fluorides and alkali metal fluorides, andcombinations thereof.
 12. The solar thermal capacitor system of claim10, wherein the molten salt has salt-forming cations selected fromammonium, calcium, iron, magnesium, potassium, pyridinium, quaternaryammocium, and sodium; and common salt-forming anions selected fromacetate, carbonate, chloride citrate, cyanide, nitrate, nitrite,phosphate and sulfate.
 13. The solar thermal capacitor system of claim12, wherein the molten salt is further composed of a metal selected fromscandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium,tantalum, chromium, molybdenum, tungsten, manganese, technetium, rheniumand lanthanoid.
 14. The solar thermal capacitor system of claim 1,wherein the molten salt includes at least one element selected from thegroup consisting of lithium, sodium, potassium, rubidium, cesium,beryllium, magnesium, calcium, strontium, and barium; at least oneelement selected from the group consisting of fluorine, chlorine,bromine, and iodine; at least one element selected from the groupconsisting of scandium, yttrium, titanium, zirconium, hafnium, vanadium,niobium, tantalum, chromium, molybdenum, tungsten, manganese,technetium, rhenium and lanthanoid (hereinafter, this element may alsobe referred to as “heavy metal”); and an organic polymer including atleast one type of a bond of carbon-oxygen-carbon and a bond ofcarbon-nitrogen-carbon.
 15. The solar thermal capacitor system of claim1, wherein the system further comprises a support to hold the solarconcentrator in a position to heat the thermal capacitor.
 16. The solarthermal capacitor system of claim 15, wherein the support comprises abase to hold the thermal capacitors and a pivot assembly to hold thesolar concentrator in position to concentrate solar light onto thethermal capacitor.
 17. The solar thermal capacitor system of claim 16,wherein the base absorbs heat.
 18. The solar thermal capacitor system ofclaim 15, wherein the base holds multiple fuel cells
 19. The solarthermal capacitor system of claim 1, wherein said thermal capacitor canbe used as heating fuel cells for cooking and heating purposes
 20. Thesolar thermal capacitor system of claim 1, wherein said thermalcapacitor includes an anode and cathode connection, and the molten saltis capable of storing electrical energy.
 21. A solar thermal capacitorsystem, comprising a solar concentrator and a portable thermal capacitorcontaining molten salt, wherein said solar concentrator is affixed on asupport pivot to follow the rotation of the sun and concentrate solarlight onto the thermal capacitor, wherein the support pivot is affixedon a base, and wherein the thermal capacitor is portable and removablefrom the base.